预期作用对大鼠皮层-丘脑神经元伤害性反应的调节

ANTICIPATION OF PAIN MODULATES CORTICAL AND THALAMIC NOCICEPTIVE RE-SPONSES IN AWAKE RATS

摘要:

目的:探索与痛觉预期特异相关的脑区,并研究预期作用对大鼠丘脑-皮层神经元伤害性反应的影响。方法:采用经典的声音-激光条件反射模型使大鼠产生痛觉的确定性预期,同时采用多通道单位放电同步记录技术观察预期状态下前扣带回(ACC)、中央杏仁核(CeA)、丘脑背内侧核(MD)以及初级躯体感觉皮层(SI)的神经元群对预期信号和随后伤害性激光刺激的反应模式。结果:(1)ACC和MD对预期信号的反应幅度和比例以及SI的抑制性反应比例在条件化后显著增加;(2)条件化能够显著增强四个脑区神经元对伤害性反应的幅度和比例,且在训练过程中增强的幅度最大。结论:ACC、MD和SI可能是参与预期信号编码的特异性脑区;预期效应,特别是预期形成过程能显著增强中枢的痛反应。

Abstract:

Objective:To explore the specific brain structures for pain anticipation and how anticipation influences cortical and thalamic nociceptive responses in awake rats.Methods:According to conventional tone-laser conditioning model,rats were trained to associate a tone(conditioned stimulus) with noxious CO2 laser pulsation(unconditioned stimulus) applied to the hind paw.Single-neuron activities in the anterior cingulated cortex(ACC),central nucleus of amygdale(CeA),medial dorsal thalamus(MD) and primary somatosensory cortex(SI) were recorded simultaneously during conditional training.Results:(1) Neuronal responses to anticipatory stimuli(tone) in ACC and MD were significantly enhanced,meanwhile the percentage of inhibitory neurons in SI increased since conditioning model was fully established.(2) The nociceptive responses in target areas were greatly enhanced by conditioning,especially in the training session.Conclusion:ACC,MD and SI might be involved in the processing of pain anticipation,which turned out to facilitate the central nervous nociceptive responses.